The Night beast is a superior variant of the dark beast. It has a chance of spawning once after purchasing the unlock Bigger and Badder for 150 Slayer reward points from any Slayer master. Like their standard variant, they will only use their Magic attack if attacked first (which will always be the case since they are not aggressive) or from afar.

The night beast has a special attack where it will briefly stop attacking then it uses Magic for three attacks which resembles Fire Blast, covering a 3x3 area dealing damage based on the player's current hitpoints. It is best to have Protect from Melee active and take the hits, as the attack will never kill the player. The attack can be avoided by simply moving away from the targeted area.